Expandable Device for Use in a Well Bore

ABSTRACT

An expandable device comprising a plurality of expandable cells. The cells may be bistable cells or other types of cells that are expanded from a contracted position towards an expanded position. Additionally, the cells may be combined with locking mechanisms to hold the structure in an expanded position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the benefit of priorityto U.S. application Ser. No. 11/150,836, filed Jun. 10, 2005, which is acontinuation of U.S. application Ser. No. 10/050,468, filed Jan. 16,2002, which claims the benefit of priority to U.S. ProvisionalApplication No. 60/261,749, filed Jan. 16, 2001, and U.S. ProvisionalApplication No. 60/296,875, filed Jun. 8, 2001, which applications areincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to expandable devices, and particularlyto devices formed from one or more expandable cells that facilitatetransition of the device from a contracted state to an expanded state.

BACKGROUND OF THE INVENTION

In a variety of applications and environments, it would be beneficial tohave a device able to transition from a contracted state to an expandedstate. Such devices can comprise planar members, tubular members,rectangular members and a variety of other configurations. Exemplaryapplications include medical applications in which expandable devices,such as stents, are deployed at a desired location and then expanded.Another exemplary application comprises the use of expandables in theretrieval of various fluids, e.g. oil, from subterranean locations.

For example, fluids such as oil, natural gas and water are obtained fromsubterranean geologic formations (a “reservoir”) by drilling a well thatpenetrates the fluid-bearing formation. Once a wellbore has been drilledto a certain depth, the borehole wall typically is supported to preventcollapse. During the drilling and use of a wellbore, various tubularmembers, such as liners, casings, sandscreens, etc. are deployed withinthe wellbore.

Various methods have been developed for radially expanding tubulars by,for instance, pulling an expansion mandrel through the tubular toplastically deform the tubular in a radially outward direction. Such anapproach, however, requires a large amount of force to achieve thedesired expansion.

The medical industry, oil industry and a variety of other industriesutilize certain types of expandables or would benefit from the use ofexpandables in numerous applications. However, there are very fewexisting devices that are readily expandable at a desired location. Ofthe devices that do exist, substantial forces are required to create theexpansion. Also, substantial plastic deformation often occurs which canlimit the selection of available materials for a given expandabledevice. The present invention is directed to overcoming, or at leastreducing, the effects of one or more of the problems set forth above.

SUMMARY OF THE INVENTION

The present invention relates generally to expandable devices that maybe used, for example, in subterranean environments. In one embodiment ofthe invention, the expandable device comprises one or more expandablecells that facilitate expansion of the device. By way of example, atubular may be formed with a plurality of expandable cells thatfacilitate radial expansion of the device from a collapsed or contractedstate to an expanded state. A variety of cell types and cell designs maybe utilized depending on the application and desired parameters of theexpandable device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereafter be described with reference to theaccompanying drawings, wherein like reference numerals denote likeelements, and:

FIGS. 1A and 1B are illustrations of the forces imposed to make abistable structure;

FIGS. 2A and 2B show force-deflection curves of two bistable structures;

FIGS. 3A-3F illustrate expanded and collapsed states of three bistablecells with various thickness ratios;

FIGS. 4A and 4B illustrate a bistable expandable tubular in its expandedand collapsed states;

FIGS. 4C and 4D illustrate a bistable expandable tubular in collapsedand expanded states within a wellbore;

FIGS. 5A and 5B illustrate an expandable packer type of deploymentdevice;

FIGS. 6A and 6B illustrate a mechanical packer type of deploymentdevice;

FIGS. 7A-7D illustrate an expandable swage type of deployment device;

FIGS. 8A-8D illustrate a piston type of deployment device;

FIGS. 9A and 9B illustrate a plug type of deployment device;

FIGS. 10A and 10B illustrate a ball type of deployment device;

FIG. 11 is a schematic of a wellbore utilizing an expandable bistabletubular;

FIG. 12 illustrates a motor driven radial roller deployment device;

FIG. 13 illustrates a hydraulically driven radial roller deploymentdevice;

FIG. 14 is a cross sectional view of one embodiment of the packer of thepresent invention;

FIG. 15 is a cross sectional view of another embodiment of the packer ofthe present invention;

FIG. 16 is a side elevation view of an embodiment of the presentinvention in a contracted state;

FIG. 17 is a side elevation view of an embodiment of the presentinvention in an expanded state;

FIGS. 18 A-C are schematic views of an alternative embodiment of thepresent invention;

FIG. 19 is a perspective view of an alternative embodiment of thepresent invention;

FIG. 20 is a schematic view of an alternative embodiment of the presentinvention;

FIG. 21 is a schematic view of an alternative embodiment of the presentinvention;

FIGS. 22 A-B are partial side elevational view of an embodiment of thepresent invention in the contracted and expanded positions respectively;

FIGS. 23 A-B are partial side elevational views of an embodiment of thepresent invention in the contracted and expanded positions respectively;

FIGS. 24 A-B are side elevational views of an alternate embodiment of anexpandable cell in its contracted and expanded positions, respectively;

FIGS. 25 A-B are side elevational views of a cell similar to thatillustrated in FIGS. 24 A-B deployed in its contracted and expandedpositions, respectively;

FIGS. 26 A-B illustrate another embodiment of expandable cells displayedin their contracted and expanded positions, respectively;

FIGS. 27 A-B illustrate another embodiment of expandable cells displayedin their contracted and expanded positions, respectively;

FIGS. 28 A-B illustrate another embodiment of expandable cells displayedin their contracted and expanded positions, respectively;

FIGS. 29 A-B illustrate another embodiment of expandable cells displayedin their contracted and expanded positions, respectively;

FIGS. 30 A-B illustrate another embodiment of an expandable celldisplayed in its contracted and expanded position, respectively;

FIGS. 31 A-C illustrate a cell with energy storage members moving from acontracted state to an expanded state;

FIGS. 32A-32B illustrate another embodiment of the cell illustrated inFIGS. 31 A-C in a contracted position and expanded position,respectively;

FIG. 33 illustrates another exemplary expandable cell design;

FIG. 34 illustrates another exemplary expandable cell design;

FIGS. 35 A-D illustrate an exemplary locking mechanism moving throughvarious stages from a closed position to an open, locked position;

FIGS. 36 A-D illustrate another embodiment of the locking mechanism ofFIG. 35;

FIG. 37 illustrates a locking mechanism combined with an expandablecell;

FIG. 38A-B illustrate an expandable cell combined with a lockingmechanism in a collapsed and expanded position, respectively;

FIG. 39 illustrates an expandable cell with another embodiment of alocking mechanism;

FIGS. 40 A-B illustrate an individual expandable cell and a plurality ofexpandable cells, respectively, combined with corresponding lockingmechanisms;

FIGS. 41 A-B illustrate another embodiment of combined expandable cellsand locking mechanisms in collapsed and expanded positions,respectively; and

FIG. 42 is a schematic representation of the combination of expandablecells having differing sizes and configurations in a single expandabledevice.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following describes a variety of expandable devices that utilizeexpandable cells to facilitate expansion of the device from a contractedstate to an expanded state. Various expansion techniques, expandablecell designs, and locking mechanisms are described, and typically thedescription is related to one or more exemplary applications. Forexample, the cells are described for use in tubular components, such astubulars used in the oil production industry. However, this applicationis only an exemplary application to demonstrate the applicability of thevarious cells and locking mechanisms described herein. The descriptionshould not be construed as limiting the application of such expandabledevices to the particular environments or applications described herein.Rather the techniques for formulating expandable devices can have a widerange of applications in other environments and industries.

As described below, exemplary expandable devices may or may not comprisebistable cells. Whether bistable or not, the expandable cells facilitateexpansion of a given device between a contracted state and an expandedstate for a variety of operations or procedures. The selection of aparticular type of expandable cell depends on a variety of factorsincluding environment, degree of expansion, materials available, etc.

Bistable devices used in the present invention can take advantage of aprinciple illustrated in FIGS. 1A and 1B. FIG. 1A shows a rod 10 fixedat each end to rigid supports 12. If the rod 10 is subjected to an axialforce it begins to deform as shown in FIG. 1B. As the axial force isincreased rod 10 ultimately reaches its Euler buckling limit anddeflects to one of the two stable positions shown as 14 and 15. If thebuckled rod is now clamped in the buckled position, a force at rightangles to the long axis can cause the rod to move to either of thestable positions but to no other position. When the rod is subjected toa lateral force it must move through an angle β before deflecting to itsnew stable position.

Bistable systems are characterized by a force deflection curve such asthose shown in FIGS. 2A and 2B. The externally applied force 16 causesthe rod 10 of FIG. 1B to move in the direction X and reaches a maximum18 at the onset of shifting from one stable configuration to the other.Further deflection requires less force because the system now has anegative spring rate and when the force becomes zero the deflection tothe second stable position is spontaneous.

The force deflection curve for this example is symmetrical and isillustrated in FIG. 2A. By introducing either a precurvature to the rodor an asymmetric cross section the force deflection curve can be madeasymmetric as shown in FIG. 2B. In this system the force 19 required tocause the rod to assume one stable position is greater than the force 20required to cause the reverse deflection. The force 20 must be greaterthan zero for the system to have bistable characteristics.

Bistable structures, sometimes referred to as toggle devices, have beenused in industry for such devices as flexible discs, over center clamps,hold-down devices and quick release systems for tension cables (such asin sailboat rigging backstays).

Instead of using the rigid supports as shown in FIGS. 1A and 1B, a cellcan be constructed where the restraint is provided by curved strutsconnected at each end as shown in FIGS. 3A-3F. If both struts 21 and 22have the same thickness as shown in FIGS. 3A and 3B, the forcedeflection curve is linear and the cell lengthens when compressed fromits open position FIG. 3B to its closed position FIG. 3A. If the cellstruts have different thicknesses, as shown in FIGS. 3C-3F, the cell hasthe force deflection characteristics shown in FIG. 2B, and does notchange in length when it moves between its two stable positions. Anexpandable bistable tubular can thus be designed so that as the radialdimension expands, the axial length remains constant. In one example, ifthe thickness ratio is over approximately 2:1, the heavier strut resistslongitudinal changes. By changing the ratio of thick-to-thin strutdimensions, the opening and closing forces can be changed. For example,FIGS. 3C and 3D illustrate a thickness ratio of approximately 3:1, andFIGS. 3E and 3F illustrate a thickness ratio of approximately 6:1.

An expandable bore bistable tubular, such as casing, a tube, a patch, orpipe, can be constructed with a series of circumferential bistableconnected cells 23 as shown in FIGS. 4A and 4B, where each thin strut 21is connected to a thick strut 22. The longitudinal flexibility of such atubular can be modified by changing the length of the cells and byconnecting each row of cells with a compliant link. Further, the forcedeflection characteristics and the longitudinal flexibility can also bealtered by the design of the cell shape. FIG. 4A illustrates anexpandable bistable tubular 24 in its expanded configuration while FIG.4B illustrates the expandable bistable tubular 24 in its contracted orcollapsed configuration. Within this application the term “collapsed” isused to identify the configuration of the bistable element or device inthe stable state with the smallest diameter, it is not meant to implythat the element or device is damaged in any way. In the collapsedstate, bistable tubular 24 is readily introduced into a wellbore 29, asillustrated in FIG. 4C. Upon placement of the bistable tubular 24 at adesired wellbore location, it is expanded, as illustrated in FIG. 4D.

The geometry of the bistable cells is such that the tubularcross-section can be expanded in the radial direction to increase theoverall diameter of the tubular. As the tubular expands radially, thebistable cells deform elastically until a specific geometry is reached.At this point the bistable cells move, e.g. snap, to a final expandedgeometry. With some materials and/or bistable cell designs, enoughenergy can be released in the elastic deformation of the cell (as eachbistable cell snaps past the specific geometry) that the expanding cellsare able to initiate the expansion of adjoining bistable cells past thecritical bistable cell geometry. Depending on the deflection curves, aportion or even an entire length of bistable expandable tubular can beexpanded from a single point.

In like manner if radial compressive forces are exerted on an expandedbistable tubular, it contracts radially and the bistable cells deformelastically until a critical geometry is reached. At this point thebistable cells snap to a final collapsed structure. In this way theexpansion of the bistable tubular is reversible and repeatable.Therefore the bistable tubular can be a reusable tool that isselectively changed between the expanded state as shown in FIG. 4A andthe collapsed state as shown in FIG. 4B.

In the collapsed state, as in FIG. 4B, the bistable expandable tubularis easily inserted into the wellbore and placed into position. Adeployment device is then used to change the configuration from thecollapsed state to the expanded state.

In the expanded state, as in FIG. 4A, design control of the elasticmaterial properties of each bistable cell can be such that a constantradial force can be applied by the tubular wall to the constrainingwellbore surface. The material properties and the geometric shape of thebistable cells can be designed to give certain desired results.

One example of designing for certain desired results is an expandablebistable tubular string with more than one diameter throughout thelength of the string. This can be useful in boreholes with varyingdiameters, whether designed that way or as a result of unplannedoccurrences such as formation washouts or keyseats within the borehole.This also can be beneficial when it is desired to have a portion of thebistable expandable device located inside a cased section of the wellwhile another portion is located in an uncased section of the well. FIG.11 illustrates one example of this condition. A wellbore 40 is drilledfrom the surface 42 and comprises a cased section 44 and an openholesection 46. An expandable bistable device 48 having segments 50, 52 withvarious diameters is placed in the well. The segment with a largerdiameter 50 is used to stabilize the openhole section 46 of the well,while the segment having a reduced diameter 52 is located inside thecased section 44 of the well.

Bistable collars or connectors 24 A (see FIG. 4C) can be designed toallow sections of the bistable expandable tubular to be joined togetherinto a string of useful lengths using the same principle as illustratedin FIGS. 4A and 4B. This bistable connector 24 A also incorporates abistable cell design that allows it to expand radially using the samemechanism as for the bistable expandable tubular component. Exemplarybistable connectors have a diameter slightly larger than the expandabletubular sections that are being joined. The bistable connector is thenplaced over the ends of the two sections and mechanically attached tothe expandable tubular sections. Mechanical fasteners such as screws,rivets or bands can be used to connect the connector to the tubularsections. The bistable connector typically is designed to have anexpansion rate that is compatible with the expandable tubular sections,so that it continues to connect the two sections after the expansion ofthe two segments and the connector.

Alternatively, the bistable connector can have a diameter smaller thanthe two expandable tubular sections joined. Then, the connector isinserted inside of the ends of the tubulars and mechanically fastened asdiscussed above. Another embodiment would involve the machining of theends of the tubular sections on either their inner or outer surfaces toform an annular recess in which the connector is located. A connectordesigned to fit into the recess is placed in the recess. The connectorwould then be mechanically attached to the ends as described above. Inthis way the connector forms a relatively flush-type connection with thetubular sections.

A conveyance device 31 transports the bistable expandable tubularlengths and bistable connectors into the wellbore and to the correctposition. (See FIGS. 4C and 4D). The conveyance device may utilize oneor more mechanisms such as wireline cable, coiled tubing, coiled tubingwith wireline conductor, drill pipe, tubing or casing.

A deployment device 33 can be incorporated into the overall assembly toexpand the bistable expandable tubular and connectors. (See FIGS. 4C and4D). Deployment devices can be of numerous types such as an inflatablepacker element, a mechanical packer element, an expandable swage, apiston apparatus, a mechanical actuator, an electrical solenoid, a plugtype apparatus, e.g. a conically shaped device pulled or pushed throughthe tubing, a ball type apparatus or a rotary type expander as furtherdiscussed below.

An inflatable packer element is shown in FIGS. 5A and 5B and is a devicewith an inflatable bladder, element, or bellows incorporated into thebistable expandable tubular system bottom hole assembly. In theillustration of FIG. 5A, the inflatable packer element 25 is locatedinside the entire length, or a portion, of the initial collapsed statebistable tubular 24 and any bistable expandable connectors (not shown).Once the bistable expandable tubular system is at the correct deploymentdepth, the inflatable packer element 25 is expanded radially by pumpingfluid into the device as shown in FIG. 5B. The inflation fluid can bepumped from the surface through tubing or drill pipe, a mechanical pump,or via a downhole electrical pump which is powered via wireline cable.As the inflatable packer element 25 expands, it forces the bistableexpandable tubular 24 to also expand radially. At a certain expansiondiameter, the inflatable packer element causes the bistable cells in thetubular to reach a critical geometry where the bistable “snap” effect isinitiated, and the bistable expandable tubular system expands to itsfinal diameter. Finally the inflatable packer element 25 is deflated andremoved from the deployed bistable expandable tubular 24.

A mechanical packer element is shown in FIGS. 6A and 6B and is a devicewith a deformable plastic element 26 that expands radially whencompressed in the axial direction. The force to compress the element canbe provided through a compression mechanism 27, such as a screwmechanism, cam, or a hydraulic piston. The mechanical packer elementdeploys the bistable expandable tubulars and connectors in the same wayas the inflatable packer element. The deformable plastic element 26applies an outward radial force to the inner circumference of thebistable expandable tubulars and connectors, allowing them in turn toexpand from a contracted position (see FIG. 6A) to a final deploymentdiameter (see FIG. 6B).

An expandable swage is shown in FIGS. 7A-7D and comprises a series offingers 28 that are arranged radially around a conical mandrel 30. FIGS.7A and 7C show side and top views respectively. When the mandrel 30 ispushed or pulled through the fingers 28 they expand radially outwards,as illustrated in FIGS. 7B and 7D. An expandable swage is used in thesame manner as a mechanical packer element to deploy a bistableexpandable tubular and connector.

A piston type apparatus is shown in FIGS. 8A-8D and comprises a seriesof pistons 32 facing radially outwardly and used as a mechanism toexpand the bistable expandable tubulars and connectors. When energized,the pistons 32 apply a radially directed force to deploy the bistableexpandable tubular assembly as per the inflatable packer element. FIGS.8A and 8C illustrate the pistons retracted while FIGS. 8B and 8D showthe pistons extended. The piston type apparatus can be actuatedhydraulically, mechanically or electrically.

A plug type actuator is illustrated in FIGS. 9A and 9B and comprises aplug 34 that is pushed or pulled through the bistable expandabletubulars 24 or connectors as shown in FIG. 9A. The plug is sized toexpand the bistable cells past their critical point where they will snapto a final expanded diameter as shown in FIG. 9B.

A ball type actuator is shown in FIGS. 10A and 10B and operates when anoversized ball 36 is pumped through the middle of the bistableexpandable tubulars 24 and connectors. To prevent fluid losses throughthe cell slots, an expandable elastomer based liner 38 is run inside thebistable expandable tubular system. The liner 38 acts as a seal andallows the ball 36 to be hydraulically pumped through the bistabletubular 24 and connectors. The effect of pumping the ball 36 through thebistable expandable tubulars 24 and connectors is to expand the cellgeometry beyond the critical bistable point, allowing full expansion totake place as shown in FIG. 10B. Once the bistable expandable tubularsand connectors are expanded, the elastomer sleeve 38 and ball 36 arewithdrawn.

Radial roller type actuators also can be used to expand the bistabletubular sections. FIG. 12 illustrates a motor driven expandable radialroller tool. The tool comprises one or more sets of arms 58 that areexpanded to a set diameter by means of a mechanism and pivot. On the endof each set of arms is a roller 60. Centralizers 62 can be attached tothe tool to locate it correctly inside the wellbore and the bistabletubular 24. A motor 64 provides the force to rotate the whole assembly,thus turning the roller(s) circumferentially inside the wellbore. Theaxis of the roller(s) is such as to allow the roller(s) to rotate freelywhen brought into contact with the inner surface of the tubular. Eachroller can be conically-shaped in section to increase the contact areaof roller surface to the inner wall of the tubular. The rollers areinitially retracted and the tool is run inside the collapsed bistabletubular. The tool is then rotated by the motor 64, and rollers 60 aremoved outwardly to contact the inner surface of the bistable tubular.Once in contact with the tubular, the rollers are pivoted outwardly agreater distance to apply an outwardly radial force to the bistabletubular. The outward movement of the rollers can be accomplished viacentrifugal force or an appropriate actuator mechanism coupled betweenthe motor 64 and the rollers 60.

The final pivot position is adjusted to a point where the bistabletubular can be expanded to the final diameter. The tool is thenlongitudinally moved through the collapsed bistable tubular, while themotor continues to rotate the pivot arms and rollers. The rollers followa shallow helical path 66 inside the bistable tubular, expanding thebistable cells in their path. Once the bistable tubular is deployed, thetool rotation is stopped and the roller retracted. The tool is thenwithdrawn from the bistable tubular by a conveyance device 68 that alsocan be used to insert the tool.

FIG. 13 illustrates a hydraulically driven radial roller deploymentdevice. The tool comprises one or more rollers 60 that are brought intocontact with the inner surface of the bistable tubular by means of ahydraulic piston 70. The outward radial force applied by the rollers canbe increased to a point where the bistable tubular expands to its finaldiameter. Centralizers 62 can be attached to the tool to locate itcorrectly inside the wellbore and bistable tubular 24. The rollers 60are initially retracted and the tool is run into the collapsed bistabletubular 24. The rollers 60 are then deployed and push against the insidewall of the bistable tubular 24 to expand a portion of the tubular toits final diameter. The entire tool is then pushed or pulledlongitudinally through the bistable tubular 24 expanding the entirelength of bistable cells 23. Once the bistable tubular 24 is deployed inits expanded state, the rollers 60 are retracted and the tool iswithdrawn from the wellbore by the conveyance device 68 used to insertit. By altering the axis of the rollers 60, the tool can be rotated viaa motor as it travels longitudinally through the bistable tubular 24.

Power to operate the deployment device can be drawn from one or acombination of sources such as: electrical power supplied either fromthe surface or stored in a battery arrangement along with the deploymentdevice, hydraulic power provided by surface or downhole pumps, turbinesor a fluid accumulator, and mechanical power supplied through anappropriate linkage actuated by movement applied at the surface orstored downhole such as in a spring mechanism.

The bistable expandable tubular system is designed so the internaldiameter of the deployed tubular is expanded to maintain a maximumcross-sectional area along the expandable tubular. This feature enablesmono-bore wells to be constructed and facilitates elimination ofproblems associated with traditional wellbore casing systems where thecasing outside diameter must be stepped down many times, restrictingaccess, in long wellbores.

The bistable expandable tubular system can be applied in numerousapplications such as an expandable open hole liner where the bistableexpandable tubular 24 is used to support an open hole formation byexerting an external radial force on the wellbore surface. As bistabletubular 24 is radially expanded, the tubular moves into contact with thesurface forming wellbore 29. These radial forces help stabilize theformations and allow the drilling of wells with fewer conventionalcasing strings. The open hole liner also can comprise a material, e.g. awrapping, that reduces the rate of fluid loss from the wellbore into theformations. The wrapping can be made from a variety of materialsincluding expandable metallic and/or elastomeric materials. By reducingfluid loss into the formations, the expense of drilling fluids can bereduced and the risk of losing circulation and/or borehole collapse canbe minimized.

Liners also can be used within wellbore tubulars for purposes such ascorrosion protection. One example of a corrosive environment is theenvironment that results when carbon dioxide is used to enhance oilrecovery from a producing formation. Carbon dioxide (CO₂) readily reactswith any water (H₂O) that is present to form carbonic acid (H₂CO₃).Other acids can also be generated, especially if sulfur compounds arepresent. Tubulars used to inject the carbon dioxide as well as thoseused in producing wells are subject to greatly elevated corrosion rates.The present invention can be used to place protective liners, e.g. abistable tubular 24, within an existing tubular to minimize thecorrosive effects and to extend the useful life of the wellboretubulars.

Another exemplary application involves use of the bistable tubular 24 asan expandable perforated liner. The open bistable cells in the bistableexpandable tubular allow unrestricted flow from the formation whileproviding a structure to stabilize the borehole.

Still another application of the bistable tubular 24 is as an expandablesand screen where the bistable cells are sized to act as a sand controlscreen. Also, a filter material can be combined with the bistabletubular as explained below. For example, an expandable screen elementcan be affixed to the bistable expandable tubular. The expandable screenelement can be formed as a wrapping around bistable tubular 24. It hasbeen found that the imposition of hoop stress forces onto the wall of aborehole will in itself help stabilize the formation and reduce oreliminate the influx of sand from the producing zones, even if noadditional screen element is used.

The above described bistable expandable tubulars can be made in avariety of manners such as: cutting appropriately shaped paths throughthe wall of a tubular pipe thereby creating an expandable bistabledevice in its collapsed state; cutting patterns into a tubular pipethereby creating an expandable bistable device in its expanded state andthen compressing the device into its collapsed state; cuttingappropriate paths through a sheet of material, rolling the material intoa tubular shape and joining the ends to form an expandable bistabledevice in its collapsed state; or cutting patterns into a sheet ofmaterial, rolling the material into a tubular shape, joining theadjoining ends to form an expandable bistable device in its expandedstate and then compressing the device into its collapsed state.

The materials of construction for the bistable expandable tubulars caninclude those typically used within the oil and gas industry such ascarbon steel. They can also be made of specialty alloys (such as amonel, inconel, hastelloy or tungsten-based alloys) if the applicationrequires.

The configurations shown for the bistable tubular 24 are illustrative ofthe operation of a basic bistable cell. Other configurations may besuitable, but the concept presented is also valid for these othergeometries.

In FIGS. 14 and 15, a packer 80 formed of bistable cells is illustrated.The packer 80 has a tubular 82 formed of bistable cells 83, such asthose previously discussed. In addition, the packer 80 has at least oneseal 84 along at least a portion of its length. An exemplary seal 84 mayinclude one or more layers positioned internally, externally, or bothwith respect to tubular 82. Additionally, the layer(s) may be intermixedwith the openings formed in the cells.

FIG. 14 illustrates an embodiment having an internal and an externalseal 84. FIG. 15 illustrates a packer 80 having only an internal seal84. The seal 84 may be formed of an elastomer or other material.Further, the properties of the seal 84 allow it to at least match theexpansion ratio of the tubular 82. Folds or other design characteristicsof the seal 84 may be used to facilitate the expansion.

Also, a resin or catalyst 85 may be used to allow the seal 84 to hardenafter setting. In one alternative embodiment a resin or other flowablematerial is placed between the layers of seals 84 (as in FIG. 14). Oncethe packer 80 is placed in the well and expanded, the flowable materialmay be hardened or otherwise altered to improve the sealingcharacteristics of the packer 80. In some applications, hardening of theresin or other material requires heating of the material by a servicetool. The packer 80 can be expanded as described herein, and maycomprise a variety of bistable cells. In one embodiment of use, thepacker 80 is deployed on a run-in tool that includes an expanding tool.The packer 80 is positioned at the desired location and expanded to sealagainst the walls of the casing or other tubular. Typically, the packer80 is connected to a tubing or other conduit that extends downhole belowthe packer 80. The packer 80 provides a seal in the annulus to preventor restrict fluid flow longitudinally in the well (the typical use forpackers). The present invention also may act as a well anchor whichincludes or excludes the seal 84.

In FIG. 16, an alternative embodiment is illustrated in which the packer80 forms a portion of a conduit. In the embodiment shown, a well conduit90 (such as a tubing) has a portion (marked as the packer 80) that iscut to form the bistable cells. The packer portion 80 has a seal 84thereon as previously described. In FIG. 16, a portion of the sealmaterial 84 is illustrated as removed to reveal the bistable cells 83 inthe underlying tubular 82. In FIG. 17, the packer portion 80 isillustrated in its expanded state. It should be noted that in typicalapplications the well conduit 90 which does not have bistable cellsformed therein, does not expand. Thus, one embodiment for attaching thewell conduit to the packer 80 is to form the packer 80 as an integralpart of the well conduit 90 (note that a welded connection resemblesthis embodiment and is an alternative method of forming the presentinvention). Other methods include conventional methods of non-integralconnection.

In alternative embodiments, the well conduit has a plurality of bistablecell packers 80 formed thereon. In yet another alternative embodiment, aportion or portions 91 of the well conduit in addition to the packerportions 80 are formed of bistable cells so that these other portionsalso undergo expansion (see FIG. 17). The other portions may or may nothave a material applied thereto. For example, the other portion may havea screen or filter material applied thereto to provide a well sandscreen.

Referring to FIGS. 18 A-C, an alternative design of the presentinvention is illustrated in a schematic, partial cross-sectional view.The expandable packer is shown in the retracted and expanded states,respectively, and in partial side elevational view (FIG. 18C). Thepacker shown includes a base tubular 82 formed of thin struts 21 andthick struts 22 forming bistable cells 23/83 as previously described.Slats 92 are attached to the tubing 82 at one edge and extend generallylongitudinally in the embodiment shown (see FIG. 18C). Specifically,each slat 92 is attached to the tubing 82 at the thick struts 22, andthe width of the slats is such that they overlap at least the adjacentslat when the tubing 82 is in the expanded state. Although illustratedas having a slat attached to each of the thick struts, the packer mayhave a slat attached to alternate thick struts 22 or in otherconfigurations. Furthermore, the slats may extend in a direction otherthan the longitudinal direction. The slats 92 slide over one anotherduring expansion so that the outside of the tubing 82 is covered by theoverlapping slats 92.

A seal 84 may be attached to the slats 92 to provide the seal for thepacker. Although shown in the figures as folded, the seal 84, may haveother characteristics that facilitate its ability to expand with theslats 92 and tubular 82. Also, the seal 84 may have othercharacteristics previously mentioned (e.g., resin, internal seal, etc.).

It should be noted that although described as a packer, the presentinvention may be used to provide isolation over a long length as opposedto a traditional packer or downhole tool which generally seals only arelatively short longitudinal distance. Thus, the present invention maybe used in a manner similar to a casing to provide isolation for anextended length.

In FIG. 19, a perspective view of packer 80 (or isolation device) havinga plurality of slats 92 attached thereto is illustrated in anoverlapping arrangement as previously described. The tubing 82 includesend extensions 94 that extend longitudinally from the endmost cells. Theslats 92 may be attached to the end extensions 94, to certain portionsof the thick struts 22 and/or to certain thick struts 22. In oneembodiment, for example, the struts 92 are attached to the thick strutswhich are longitudinally aligned with the end extensions 94. Althoughgenerally shown as attached at an edge of the slats 92, the slats alsomay attach to the tubing 82 at a position intermediate the edges.

In FIG. 20, an expandable tubing (or conduit) 90 is illustratedpositioned in a well 100. The conduit 90 includes a plurality of spacedpackers 80 or expandable sealing devices. The expandable packers 80engage the wellbore wall preventing annular flow thereby. Therefore, anymicroannulus formed between the expandable tubing 90 and the well 100(which may include a casing) is sealed in the longitudinal direction torestrict or prevent unwanted flow thereby. The conduit 90 may includeone or more such packers 80, as desired, to control the flow. Further,the packers 80 may be spaced at regular intervals or at some otherpredetermined spacing to control the flow in the annulus as needed.

In one example, illustrated schematically in FIG. 21, the individualjoints of tubing 90 are interconnected by a packer 80 tocompartmentalize each joint of conduit from the adjacent joint(s). Thepacker 80 can be a separate connector as shown in FIG. 21 or it can beformed as part of the joint. Accordingly, the packer 80 can bepositioned at an end of the joint 90, in the middle of the joint 90, orat any other location along its length. In one embodiment both conduit90 and packers 80, of FIGS. 20 and 21, are formed of bistable cells.

Referring generally to FIGS. 22 A-B, an alternative embodiment of thepresent invention is disclosed. The device shown in these figures may beused as a packer, hanger, casing patch, or other device requiringexpansion and is generally referred to herein in reference to thesefigures as an expandable tubular 120 for ease of description. Theexpandable tubular 120 comprises a series of cells 122 formed therein,such as by laser cutting, jet cutting, water jet cutting or othermanufacturing methods. The cells 122 are oriented such that a number oflongitudinal struts 24 are formed on the expandable tubular 120. Thus,as shown in the figures, the longitudinal struts 124 lie betweenlongitudinal lengths of cells 122 with the cells 122 having relativelythinner struts 126 extending between adjacent longitudinal struts 124.As shown in the figures, as the adjacent longitudinal struts 124 aremoved longitudinally relative to one another (e.g. in oppositedirections), the cells 122 open to expand the structure radially. Notall of the longitudinal struts 124 must move; alternate longitudinalstruts 124 may be moved while the other struts remain stationary. Therelative movement of the longitudinal struts 124 provides the expansionof the cells 122 and the expandable tubular 120. This type of cell is anexample of an expandable cell that is not bistable.

A locking mechanism 128 may be used to maintain the expanded position ofthe expandable tubular 120. As shown in FIGS. 22 A-B, the expandabletubular may comprise one or more locking mechanisms 128 spaced along thelength of the expandable tubular 120 and spaced radially about theexpandable tubular 120. One embodiment of the locking mechanism is shownin FIGS. 23 A-B. In the embodiment shown, the locking mechanism 128comprises a detent (or finger) 130 extending from one longitudinal strut124 and cooperating with a set of ratchet teeth 132 provided on anotherlongitudinal strut 124. The ratchet teeth 132 extend from a ramp area134 of the longitudinal strut 124 to accommodate for the relativemovement of the detent 130 to the longitudinal strut 124 having theratchet teeth 132. The ratchet teeth 132 generally allow movement of thedetent 130 thereon in a first direction associated with the expansion ofthe expandable tubular 120, and prevent movement of the detent 130 inthe opposite direction. Once in the expanded position, the detent 130acts as a locked strut preventing retraction of the expandable tubular120. To increase the structural integrity of the expanded tubular 120and to resist forces tending to move the expandable tubular 120 from anexpanded state or position to a reduced position, the expandable tubular120 may include a plurality of locking mechanisms 128.

Although shown as a ratchet, as an alternative the locking mechanism mayhave fewer discrete positions, such as one, in which the detent locks inthe fully expanded position only. In another embodiment the detent maycomprise a resilient finger biased toward an extended position thatsnaps into a groove in an adjacent longitudinal strut 124. Likewise, theadjacent struts 124 may each have resilient detents that cooperate tolock the device in the expanded position only upon the tubular 120achieving the expanded position. These are only a few examples of themany possible alternatives for the locking mechanism 128.

Also, various other tubular expansion mechanisms and expandable cellsmay be utilized, such as expandable tubulars and other devices. Forexample, details of one type of expandable cell are illustrated in FIGS.24A, 24B, 25A and 25B. In this embodiment, as in other embodiments, thecell is transitioned from a compressed state to an expanded state.

During movement from the compressed state to the expanded state anddepending upon the environmental conditions as well as the materialsused, material thickness and other design parameters of the cell anddevices formed from the cell, some areas of the cell and struts mayexperience plastic deformation. In FIGS. 24A, 24B, 25A and 25Balternative embodiments of a cell are illustrated in compressed andexpanded states. In these embodiments, one of the struts 21 (shown asthe thinner, upper strut) has thinned portions 140 that serve asflexible hinges or joints. The thinned portions 140 are preferablyplaced at areas where plastic deformation of the strut is likely tooccur as the strut moves from a compressed to an expanded state. Thus,for example, the thinned portions 140 may be placed near theintersection of the struts 21, 22 to provide an area that is lesssusceptible to plastic deformation. Although the figures show aplurality of thinned portions 140, the strut may include a singlethinned portion 140, for example, at an area of increased plasticdeformation. Also, the thinned portions 140 may be placed in otherpositions along the struts 21, 22 for other purposes. The thinned areas140 define linkages 142 there between that comprise portions which aregenerally thicker than the thinned portions 140. Placing a plurality ofthinned portions 140 along the length of a strut 21, 22 produces aplurality of linkages 142.

Another factor in determining the positioning of the thinned portions140 is the number, placement, and design of the linkages. Although shownin the figures as having a uniform thickness, the linkages 142 may alsohave a variation in thickness to further tailor the expansion,contraction, and other characteristics of the cell as desired.Therefore, in one broad aspect of the inventions, at least one of thestruts 21, 22 has a thickness that varies. Also, other factors may beconsidered in placement of the thinned portions 140 and the thicknessvariations of the struts 21, 22. Also, the thinned portions may occur atthe intersection of the struts 21, 22.

In FIGS. 24A and 24B a cell with three linkages 142 is illustrated; andin FIGS. 25A and 25B a cell with two linkages is illustrated. AlthoughFIGS. 24A-25B disclose only a single cell, the cells may be incorporatedinto a tool, such as a tube, having a plurality of cells such as thatshown in FIGS. 4A and 4B. The figures illustrate a single cell to moreclearly show the basic concept and the cell design. The handles shown inthe figures are not a part of the cell structure, but are merely used ontest cells to facilitate testing of the cells.

Referring generally to FIGS. 26A and 26B, another embodiment ofexpandable cells, labeled as expandable cells 150, is illustrated. Eachexpandable cell 150 comprises a thick strut 152 and one or more thinstruts 154, e.g. two thin struts 154. In the embodiment illustrated,each expandable cell 150 comprises a pair of thin struts, and each thinstrut 154 has a pair of ends 156 pivotably coupled to adjacent thickstruts, respectively. Ends 156 may comprise pins that are pivotablyreceived in corresponding sockets 158.

As the plurality of expandable cells 150 is moved from the contractedstate illustrated in FIG. 26A to the expanded state illustrated in FIG.26B, thin struts 154 deform sufficiently to permit pivoting of pins 156in their corresponding sockets 158. As illustrated best in FIG. 26B, thepairs of thin struts 154 that form each cell 150 have outlying ends 156pivotably coupled to upper attachment regions 160 of the lower thickstrut 152. The opposite ends of each pair of thin struts 154 arepivotably coupled to a lower attachment region 162 of the next upwardlyadjacent thick strut 152. It should be noted that positional terms suchas upper and lower are merely used to facilitate explanation of thelocation of various features relative to the figures provided and shouldnot be construed as limiting.

In another embodiment illustrated in FIGS. 27A and 27B, a plurality ofexpandable cells, labeled with reference numeral 164, each comprise athick strut 166 and one or more thin struts 168. Each thick strut 166 isgenerally arcuate and connected to a corresponding thin strut 168 at afixed connection region 170 disposed at a generally central locationalong the outer or convex portion of the arcuate thick strut. The outerends of each thin strut 168 are pivotably coupled to the next adjacentthick strut 166 via a pivot connection 172 that may comprise a ball andsocket.

As the plurality of cells are moved from the contracted stateillustrated in FIG. 27A to the expanded state illustrated in FIG. 27B,thin struts 168 flex or deform as their outer ends pivot at each pivotconnection 172. As with many of the other cells described herein, whenthe thin struts 168 move past their point of greatest flexure, thestored spring energy tends to force the cells 164 to their stableexpanded state illustrated in FIG. 27B. Thus, as with the bistable cellsillustrated in FIGS. 26A and 26B, cells 164 move between a stablecontracted state and a stable expanded state.

Another expandable cell embodiment is illustrated in FIGS. 28A and 28B.In this embodiment, each expandable cell 174 is formed of a thick strut176 and a thin strut 178. Each thin strut 178 has a pair of ends 180that are pivotably coupled to a thick strut. For example, a given thickstrut may comprise a pair of sockets 182 to pivotably receive pin orball shaped ends 180. Additionally, thin strut 178 is fixedly coupled toadjacent thick struts 176 in an alternating pattern. For example, eachcell in the illustrated embodiment comprises three fixed couplings 184that alternate between adjacent thick struts 176. With this design, theexpandable cells 174 again are movable between a stable contracted stateas illustrated in FIG. 28A and a stable expanded state as illustrated inFIG. 28B.

With reference to FIGS. 29A and 29B, another expandable cell design isillustrated. In this embodiment, each of a plurality of expandable cells186 comprises a thick strut 188 and at least a pair of stacked thinstruts 190, 192, respectively. Thin struts 190, 192 are generallydisposed in a stacked orientation and connected by a linking member 194.Thin strut 192 comprises a pair of ends 196 affixed to a correspondingthick strut 188. An intermediate connection region 198 of thin strut 192is affixed to the next adjacent thick strut 188, as best illustrated inFIG. 29B. Thin strut 190, on the other hand, has unattached ends 200.Ends 200 are captured in an abutting engagement with a notched region202 formed in the same thick strut 188 to which ends 196 are affixed. Asthe plurality of expandable cells 186 are moved from the contractedstate illustrated in FIG. 29A to the expanded state illustrated in FIG.29B, each pair of thin struts 190 and 192 deforms to a deflection pointwhere stored energy in the thin struts is maximized. As the thin strutsare moved past this deflection point, the stored energy is released tofacilitate expansion of the cells to their expanded state.

Of course, with any of these types of bistable cells, the degree ofexpansion may be limited by an external barrier. For example, if thebistable cells are used to form a tubular, the tubular may be expandedagainst a wellbore wall that prevents the cells from moving to theirfully expanded condition. Typically, the size of the tubular is selectedto permit expansion of the cells at least past the point of maximumdeformation. Thus, depending on the material used, the cells mayactually cooperate to apply an outwardly directed radial force againstthe wellbore wall.

Referring generally to FIGS. 30A and 30B, another expandable cell designis illustrated. Each expandable cell 204 comprises a pair of arcuatethin struts 206 pivotably coupled to a corresponding thick strut 208 ata generally centralized extended region 210 via pivot ends 212.Generally opposite pivot ends 212, thin struts 206 comprise outer pivotends 214 that are pivotably coupled to the next adjacent thick strut208. Pivot ends 212 and 214 can be formed in a variety ofconfigurations, such as ball joints, pin joints, etc. Removal of eachthin strut 206 is prevented by appropriate ligaments 216 and 218disposed at pivot ends 212 and 214, respectively. The ligaments 216 and218 are coupled between the thin strut 206 and the corresponding thickstruts 208.

In FIGS. 31A-31C, a different type of expandable cell 220 isillustrated. In this embodiment, a thick strut 222 is coupled to one ormore thin struts 224 by one or more spring elements 226. In theparticular embodiment illustrated, two spring elements 226 are formedgenerally in the shape of a horn, with the base of each horn connectedto thick strut 222 and the tip of each horn coupled to the adjacent thinstrut 224. In this embodiment, a thin strut 224 is connected to eachspring element 226 by a flexible hinge 228. The two thin struts 224 arecoupled to each other through a center beam 230 and a pair of flexiblehinges 232.

As cells 220 are expanded from a contracted state, illustrated in FIG.31A, to an expanded state, illustrated in FIG. 31 C, spring elements 226flex outwardly and store spring energy. With this design, thin struts224 typically do not undergo substantial deformation during movementfrom the contracted state to the expanded state. Rather, spring elements226 are elastically deformed as they are forced outwardly duringmovement of center beam 230 from the contracted state to the expandedstate. When spring elements 226 are flexed outwardly, they store springenergy at least to the point of maximum flexure illustrated in FIG. 31Bwhere thin struts 224 are generally parallel with thick strut 222. Oncecenter beam 230 moves past this point of maximum stored spring energy,spring elements 226 tend to release the stored energy and move inwardly,thereby forcing thin struts 224 and center beam 230 to the expandedposition illustrated best in FIG. 31C. Deformation of hinges 228 and 232facilitates the pivoting of thin struts 224 from the contracted state tothe expanded state.

A double horn cell design is illustrated in FIGS. 32A and 32B. In thisdesign, a plurality of thick struts 236 are coupled together via thinstruts 238 and horn spring members 240. Specifically, each thin strut238 is coupled to two horn spring members 240 to permit storage of agreater amount of energy. This greater energy storage provides addedpositive energy for opening cells 234 to their expanded positions asillustrated in FIG. 32B.

In the example illustrated, each double horn cell 234 has two outer hornspring members 240, coupled to one thick strut 236, and two inner hornspring members 240, coupled to the next adjacent thick strut 236. Onethin strut 238 is coupled to each cooperating pair of inner and outerhorn spring members via appropriate hinge regions 242. Thus, as thedouble horn cells 234 are moved from the contracted state illustrated inFIG. 32A to the expanded state illustrated in FIG. 32B, cooperatingpairs of inner and outer horn spring members 240 are flexed outwardly toa point at which the thin struts 238 are generally aligned. Subsequentto this point of expansion, the horn spring members 240 begin to releasethe stored spring energy and force thin struts 238 towards the fullyexpanded state.

Other forms of spring elements also may be utilized in facilitatingexpansion of a variety of cell types. For example, in FIG. 33 anexpandable cell 244 is illustrated in which adjacent thick struts 246are coupled to a thin strut 248 by a different type of spring members250. Spring members 250 may be coiled, undulating or arranged alongother paths that accommodate the transitioning of thin strut 248 fromthe contracted state illustrated in FIG. 33 to an expanded state.

Another type of spring system is illustrated in FIG. 34 as an expandablecell 252. A pair of thick struts 254 are coupled by a pair of undulatingthin struts 256. The design of thin struts 256 incorporates a pluralityof spring elements 258 that both accommodate flexure of the thin struts256 and expansion of the cell 252 by storing and then releasing springenergy. The spring energy is released as the thin struts transition pasta point of maximum flexure towards the fully expanded state.

To secure the overall device, e.g. tubular, in the expanded position, alocking mechanism may be utilized to prevent the individual cells fromcontracting. Exemplary locking mechanisms may be associated withindividual cells, or they may be located at one or more positions alongthe expandable device. In FIGS. 35A-35D, one type of locking mechanism258 is illustrated. In this embodiment, a post 260 is slidably receivedin a corresponding recess 262. A ratchet finger 264 extends generallytransversely towards post 260. Specifically, ratchet finger 264comprises an engagement end 266 that resides in a recessed area 268 ofpost 260 when the overall device and locking mechanism 258 are in acontracted state, as illustrated in FIG. 35A.

As the device, e.g. tubular, is expanded, ratchet finger 264 is flexedaway from an adjacent support surface 270, as illustrated best in FIG.35D. The ratchet finger 264 continues to slide along the side of post260 as the device is expanded to a maximum degree illustrated in FIG.35C. When the expansion force is relaxed, any substantial movement ofpost 260 towards the contracted position is blocked by ratchet finger264, as illustrated in FIG. 35D. As post 260 attempts to move towardsits contracted state, engagement end 260 is pressed firmly intointerfering engagement with the side of post 260. Additionally, supportsurface 270 limits the movement of ratchet finger 264 in the contractingdirection. The side wall of post 260 may comprise teeth or otherinterfering features that aid in preventing movement of post 260 backtowards the contracted state.

Another exemplary locking mechanism 272 is illustrated in FIGS. 36A-36D.In this embodiment, a fork ratchet 274 is formed in the expandabledevice, such as in the wall of an expandable tubular. Fork ratchet 274comprises a pair of prongs 276 that each have a divergent end 278. Inthe contracted state, prongs 276 are received in an opening 280 having agenerally hourglass shape profile. In other words, divergent ends 278reside in a divergent or expanded portion 282 of opening 280 and must bepulled through a narrow or constricted portion 284 when the device isexpanded.

During expansion of the tubular or other device, divergent portions 282are drawn through constricted region 284 (see FIGS. 36B and 36C.) Onceprongs 276 are drawn clear of opening 280, the divergent portions 282once again spring outwardly to their normal position. In this position,divergent portions 282 are wider than the entrance to opening 280, andfork ratchet 274 is prevented from reentering opening 280. Thus, theoverall device is held in its expanded state.

Another exemplary locking mechanism 284 is illustrated in FIG. 37.Locking mechanism 284 is designed for use with horn style cells. In thespecific example illustrated, a slot 286 is formed between a pair ofspring member horns 288 within a thick strut 290 of an expandable cell292. A wedge 294 extends from an adjacent thick strut 296 into slot 286.As cell 292 is expanded, wedge 294 is drawn outwardly through slot 286.The size of the wedge tip 298 and slot outlet 300 are selected tointerfere when cell 292 is in its expanded state. This prevents flexingof horns 288 towards slot 286 and thereby inhibits collapse of theexpanded cell.

Referring generally to FIGS. 38A-41B, a variety of expandable cell andlocking mechanism combinations are illustrated. With specific referenceto FIGS. 38A and 38B, one embodiment of an expandable cell 302 comprisesthick struts 304 that are coupled together by thin struts 306 via springmembers 308. Each thick strut 304 comprises one or more, e.g. two,ratchet fingers 310 that slide along a corresponding ratchet surface 312formed on expanded regions of the thin struts 306 (see FIG. 38B).

Ratchet surface 312 may incorporate ratchet teeth to engage the end ofthe corresponding ratchet finger 310. As the expandable cell 302 istransitioned from its contracted state, as illustrated in FIG. 38A, toan expanded state, as illustrated in FIG. 38B, ratchet fingers 310 areflexed away from a support surface 314 while sliding along correspondingratchet surfaces 312. The ends of the ratchet fingers 310 do not allowsliding motion of corresponding ratchet surfaces 312 back towards thecontracted state. Furthermore, support surfaces 314 may be relied on tolimit any flexing of fingers 310 back towards the contracted position.Thus, when the expandable cell is in its expanded state, each of theratchet fingers 310 acts against a corresponding ratchet surface 312 tosupport the cell against collapse.

Another embodiment of the system is illustrated in FIG. 39 and utilizesfingers in the form of ratchet pawls 316. In this embodiment, eachratchet pawl is formed in an appropriate thick strut 304 by creating anopen area 318 configured to receive a corresponding portion 320 of thinstrut 306 when in the contracted position. Each ratchet pawl 316 maycomprise a plurality of teeth 322 positioned to engage correspondingteeth 324 extending from portion 320. Additionally, a relief cut 326 maybe formed along ratchet pawl 316 generally opposite open area 318.Relief cut 326 allows ratchet pawl 316 to flex as teeth 322 are draggedpast teeth 324 during transition of the cell from a contracted state toan expanded state. Teeth 322 and 324 are designed to prevent closure ofthe cell once expansion begins. Thus, the ratchet pawl 316 effectivelyratchets along portion 320 holding the cell at each additional degree ofexpansion. As an alternative to teeth, the ratchet pawl 316 andcooperating portion 320 may utilize other types of interfering featuresto prevent contraction of the cell.

The locking mechanisms also may be used in cooperation with expandablecells that are not necessarily bistable cells. For example, in FIG. 40Aan expandable cell 330 comprises a thin strut 332 disposed in anexpandable “wishbone” type configuration between the thick struts 334 towhich it is connected. A locking mechanism 336 cooperates with one ormore of the expandable thin struts 332 to hold the expandable cells 330,at an expanded position. As illustrated in FIG. 40B, a locking mechanism336 may be combined with each expandable cell 330, or there may bemultiple expandable cells for each locking mechanism 336.

In this embodiment, locking mechanism 336 comprises a post 338 havingexternal teeth 340. Post 338 is slidably received within an opening 342defined by one or more flexible fingers 344 having engagement tips 346that engage teeth 340. Fingers 344 flex outwardly to allow teeth 340 toslide past engagement tips 346 as the cell is expanded, but engagementtips 346 prevent post 338 from moving in a direction towards thecontracted state. Thus, once expandable cell 330 is expanded, lockingmechanism 336 prevents contraction of the cell.

A similar design is illustrated in FIGS. 41A and 41B. This designcombines the expandable cell described with reference to FIG. 40A and alocking mechanism of the type described in FIGS. 36A-36D. Thus, as theplurality of expandable cells 330 are moved from the contracted stateillustrated in FIG. 41A to the expanded state illustrated in FIG. 41B,the wishbone style thin strut is expanded. Simultaneously, prongs 276are pulled from their corresponding opening 280 to a position thatprevents reentry of fork 274 into opening 280. The locking mechanism maybe designed such that prongs 276 are withdrawn from and blocked fromreentering opening 280. Alternatively, prongs 276 may be designed forinterference with corresponding teeth or other interfering features 350disposed along the outer limit of each opening 280 to prevent returnmovement of prongs 276 into opening 280.

It also should be noted that expandable devices, such as expandabletubulars, can be formed with a variety of cells and locking mechanismshaving differing configurations, such as changes in size or type, asillustrated schematically in FIG. 42. For example, by stacking cells ofdifferent length or eccentric offset in a sheet or tube, it is possibleto design an opening bias into the structure. The expandable device maybe designed to allow certain rows of cells to open prior to other rowsof cells or for the cells to open in a predetermined pattern or at apredetermined rate. In FIG. 42, for example, an expandable device 352comprises rows of expandable cells 354. However, different rows 354 havecells of differing lengths, e.g. cells 356, 358 and 360. This allowscertain rows of cells to open prior to adjoining rows of cells, because,at least with certain cell designs, the length of the cell affects theforce required to expand the cell. Incorporating different rows of cellsinto an expandable device allows the user to know the rate of expansionfor a given deployment force and facilitates the design of deviceshaving cells which open in a predetermined sequence. Additionally, theuse of different types of cells can improve compliance of the expandabledevice when the deployment force is not uniform along the length of thedevice.

It will be understood that the foregoing description is of exemplaryembodiments of this invention, and that the invention is not limited tothe specific forms shown. For example, the expandable cells can becombined into a variety of tubulars and other expandable structures; thesize and shape of the expandable cells and locking mechanisms can beadjusted; the types of material utilized can be changed depending on thespecific application; and a variety of mechanisms may be used to expandthe cells. Also, the various cells can be formed by a variety oftechniques including laser cutting, jet cutting, water jet cutting andother formation techniques. These and other modifications may be made inthe design and arrangement of the elements without departing from thescope of the invention as expressed in the appended claims.

1-21. (canceled)
 22. An expandable device for use in a well comprising:a well device comprising a tubular member having a plurality of cellsexpandable from a closed position to an open position when the tubularmember is radially expanded, at least one cell having a curved thinstrut coupled to a curved thick strut for pivotal motion relative to thecurved thick strut, wherein the thickness ratio of the curved thickstrut to the curved thin strut determines the force required totransition the plurality of cells to the open position, and wherein thecurved thin strut and the curved thick strut are curved in the closedposition.
 23. The expandable device as recited in claim 22, wherein thetubular member is an expandable sand screen.
 24. The expandable deviceas recited in claim 22, wherein the thickness ratio is at least 2 to 1.25. The expandable device as recited in claim 22, wherein the thicknessratio is at least 3 to
 1. 26. The expandable device as recited in claim22, wherein the tubular member is sized to support an open holeformation in the well.
 27. The expandable device as recited in claim 22,wherein the device comprises one or more locking mechanisms and/orratchets.
 28. The expandable device as recited in claim 27, wherein thelocking devices and/or the ratchets are distributed along the length ofthe device and are configured to block any substantial movement towardsthe contracted position of the device.
 29. The expandable device asrecited in claim 22, wherein the cells are configured such that thetubular member can transition from the closed position to the openposition from a single point.
 30. The expandable device as recited inclaim 22, wherein the tubular member in the open position has at leasttwo diameters.
 31. An expandable device for use in supporting orstabilizing a desired region of the wall within a well bore holecomprising: a downhole well device comprising a substantially tubularexpansion member having a plurality of cells that are expandable from aclosed position to an open position, each cell having a thin strutcoupled to a thick strut; wherein the tubular expansion member when in acontracted state is readily moved along the well bore; wherein thetubular expansion member when in an expanded state can engage the wallof the well bore to provide support or stabilization of the desiredregion of the wall of the well bore; and wherein the plurality of cellscomprise at least two cell sizes in a fully expanded state.
 32. Theexpandable device as recited in claim 31, wherein the device comprisesone or more locking mechanisms and/or ratchets.
 33. The expandabledevice as recited in claim 32, wherein the locking devices and/or theratchets are distributed along the length of the device and areconfigured to block any substantial movement towards the contractedposition of the device.
 34. The expandable device as recited in claim31, wherein the plurality of cells are configured in rows about thetubular expansion member such that the rows alternate between at leasttwo cell sizes.
 35. The expandable device as recited in claim 31,wherein the tubular expansion member in the open position has at leasttwo diameters.
 36. An expandable device for use in a well comprising: awell device comprising an expansion member having a plurality of cellsand one or more locking mechanisms that comprises a ratchet, theplurality of cells being expandable from a closed position to an openposition, each cell having a thin strut pivotably coupled to a thickstrut, wherein the expansion member is readily moved along a wellborewhen the plurality of cells are in the closed position, and wherein theexpansion member is expandable by transitioning the plurality of cellsto the open position at a desired location in the wellbore.
 37. Theexpandable device as recited in claim 36, wherein the ratchet comprisesa ratchet finger having an engagement end that resides in a recessedarea of the expansion member when the cells are in the closed position.38. The expandable device as recited in claim 36, wherein the ratchetsare distributed along the length of the device and are configured toblock any substantial movement towards the closed position of thedevice.
 39. The expandable device as recited in claim 36, wherein theexpansion member in the open position has at least two diameters.
 40. Adevice for expanding a tubular structure in a well comprising: aconveyance device that brings the tubular structure into the well; and adeployment device that is configured to draw power from one or acombination of sources such as electrical power supplied either from thesurface or stored in a battery arrangement along the deployment device,hydraulic power provided by surface of downhole pumps, turbines or afluid accumulator, and mechanical power supplied through an appropriatelinkage actuated by movement applied at the surface or stored downholesuch as in a spring mechanism.